Friends of Dyke Marsh is a volunteer group dedicated to preserving, restoring and enhancing Dyke Marsh, a freshwater tidal marsh in Fairfax County on the Potomac River just south of Alexandria, Virginia. The Dyke Marsh Wildlife Preserve is administered by the National Park Service.

What Is Dyke Marsh?

The Dyke Marsh Wildlife Preserve is a freshwater, tidal marsh on the Virginia side of the Potomac River in Fairfax County. It is a unit of the George Washington Memorial Parkway, U.S. National Park Service. For more information, visit the NPS website at www.nps.gov/gwmp.

FODMers, guided by Dan Schwartz, soil scientist, Northern Virginia Soil and Water Conservation District, conducted biological water quality testing on two unnamed streams flowing into the western part of Dyke Marsh on April 2 and June 11, 2016.

The findings are disappointing, but not surprising. Most streams in Fairfax County are impaired.

Thanks to members Laura Sebastianelli and Deborah Hammer, FODMers are conducting a frog and toad survey in Dyke Marsh and other areas, as part of the FrogWatchUSA national monitoring program. People living near Dyke Marsh West have heard fewer frog and toad calls in recent years and FODM would like to document species and trends.

FODM Board member Jessica Strother, a forester, led a walk on February 27, 2016, and described three of the ecotones of the preserve: the swamp forest, the floodplain forest and the tidal marsh. She explained that trees breathe through their leaves and root system. Trees like the pumpkin ash tolerate water, but cedars like drier, upland soil.

On February 28, 2016, Dr. David Luther, George Mason University biology professor, gave a presentation to FODMers and friends on his research analyzing the effects of noise on birds’ communication, a field called “acoustic ecology.” Generally, birds sing to attract mates, to defend territories and to establish “social status,” he told the 75 attendees. In urban areas, anthropogenic noise, like the noise from traffic or gardening tools, can cause birds to change their behavior and their songs.

On February 22 at Belle Haven Park, several members of the Friends of Dyke Marsh attended and helped release 21 Canada geese that had been oiled and cleaned by staff of Tri-State Bird Rescue and Research of Newark, Delaware.

FODMers and others reported to local, state and federal authorities on February 3 that an oil sheen was in the water at the Belle Haven Marina. Two people photographed an oil sheen that day, one at the marina and one at 7831 Southdown Road, almost a mile south of Dyke Marsh. Tri-State staffers said they were called on February 4 and that they and others caught birds for a week at Roaches Run, Hains Point and Gravelly Point.

Many FODMers participated in the National Audubon Society’s annual Christmas Bird Count (CBC) in January 2016. Larry Meade, president of the Northern Virginia Bird Club, gave this report in the club’s February newsletter, The Siskin:

On the morning of January 18, 2016, the annual Martin Luther King Day of Service and winter’s coldest day so far, 20 hardy volunteers organized by the Northern Virginia Conservation Trust (NVCT) visited the Dyke Marsh Wildlife Preserve. Braving temperatures in the high teens and a brisk wind whipping across the river, the group removed English ivy climbing up trees and collected five bags and a plastic crate of trash.

In September 2015, a team from the North Carolina Botanical Garden, working with National Park Service staff and the Friends of Dyke Marsh, collected thousands of pumpkin ash seeds (by the bunch, pictured) from a score of different trees in the preserve. The team has concluded that the seeds are likely viable and in early 2016, they are drying them for long-term storage.

Among many other accomplishments, Henry David Thoreau and Thomas Jefferson were diligent phenologists. They kept detailed journals in which they recorded the timing of events in nature -- when trees leafed out, when flowers bloomed, when the ground was warm enough to plant.

FODM Membership Meetings

We have rescheduled our May 19 meeting for September 8. See below. Given the uncertainty posed by the coronavirus pandemic, we may have to make some changes. Check here and our Facebook page for updates.

Coming Events

On September 8 at 7:30 p.m., Dr. Christian Jones of George Mason University’s Potomac Science Center will give a presentation on wetlands types, trends, ecology and conservation at the Huntley Meadows Park Visitor Center, 3701 Lockheed Boulevard, Alexandria, VA 22306. An informal social will start at 7 p.m. Free.

Bird Walks Canceled Through June 10

*** NOTICE ***

In light of risks related to the coronavirus, the Friends of Dyke Marsh have canceled Sunday morning bird walks at Dyke Marsh starting March 15 and effective through June 10. We hope to resume walks on June 14. Check back here and our Facebook page for information on the future schedule.

Support FODM

Your contribution will help us preserve and restore Dyke Marsh and support special programs and studies. Thank you.

Support Dyke Marsh with Your Purchases

Amazon.com will donate .5 percent of the price of your purchases to the Friends of Dyke Marsh if you shop through smile.amazon.com. Click on the link and sign into your account or create an account.

Like Us on Facebook!

FODM is on Facebook. If you are already a Facebook member, just log in to your Facebook page and search for "Friends of Dyke Marsh". Or, click this icon and then "like" us:

Bienvenidos!

The Friends of Dyke Marsh extend a welcome to all of our friends. Click here for an invitation to the Dyke Marsh Wildlife Preserve in Spanish, which we hope will make Spanish-speaking visitors feel welcome. We hope to see you soon.

Event

Wintering Waterfowl

Tundra swan (Cygnus columbianus) Photo by Cathy Ledec.

FODM President Glenda Booth has an article in the January 2020 Zebra newspaper on waterfowl on the Potomac River in winter. Read the article here.

Loggerhead Shrikes

Sergio Harding banded the shrikes with a red band.

FODM President Glenda Booth published an article in the May-June 2018 Virginia Wildlife magazine, titled, “What’s Going on with the Butcher Bird? Visit the website here. Sightings of this bird in Northern Virginia are rare.

Water Chestnut

Water chestnut. Photo from MISC, Maryland Invasive Species Council.

Help Stop the Spread of a New Species of Water Chestnut

Be on the lookout for a new species of water chestnut (genus Trapa) (http://mdinvasives.org / iotm/june-2018/) found in the Potomac watershed, Trapa bispinosa Roxb. var. iinumai Nakano. It has been spreading since 1995 and is floating aquatic vegetation growing over the surface of a pond, lake or other fresh waterbody.

This species is identified by the seed cases having two spines instead of four found on Trapa natans. Report all invasive aquatic species to the US Geological Survey’s Nonindigenous aquatic species website (https://nas.er.usgs.gov / SightingReport.aspx).

Water chestnut (an annual) sprouts in May, spreads over the water surface and then flowers and fruits by July. It drops seeds all season until it senesces after a hard frost. To stop the spread, management by harvesting the plants by early July is very successful in eradicating the plants, but it may take several years of effort, if some seeds fall before the plants are harvested or lay dormant in the current year and sprout in a later year.